1. Field of the Invention
The present invention relates to a bearing that includes a steel backing and an aluminum alloy lining containing minor amounts of tin, silicon, lead, copper and chromium. The invention also relates to a method of manufacturing the alloy.
2. Description of Prior Developments
Bearings formed of aluminum alloys containing tin, silicon, lead and copper are known in the art. For example, U.S. Pat. No. 3,809,551 to Morisaki discloses an aluminum bearing alloy containing tin, lead, copper and antimony. U.S. Pat. No. 4,471,029 to Fukuoka et al. discloses a bearing alloy comprising aluminum and minor amounts of tin and silicon. The silicon particles have nodular or rounded configurations. Additional elements such as lead, indium, cadmium and bismuth can be incorporated in the alloy to improve the wear resistance of the alloy.
U.S. Pat. No. 4,471,033 to Fukuoka et al. discloses an aluminum base bearing alloy that comprises 5% to 11% silicon, 1.5% to 35% tin, minor amounts of an element selected from the group consisting of lead, indium, thallium, cadmium and bismuth, and minor amounts of an element selected from the group consisting of copper and magnesium. The particle size of the silicon particles is controlled by two annealing operations carried out before and after the bearing alloy strip is pressure bonded to a steel backing strip.
The first annealing operation in Fukuoka is at a temperature range between 350.degree. C. and 550.degree. C. for a time period ranging from 1.5 to 6 hours. The second post-bonding annealing operation is at a temperature range between 300.degree. C. and 400.degree. C. for a time period ranging from about 1 to 2 hours. This second post-bond anneal not only increases the cost of the alloy it also causes the tin particles to grow to a size far greater than that specified in the present invention, and also decreases the alloy hardness. Each of these factors decreases the fatigue strength of the prior art alloys to compensate for this drawback, the prior art requires the addition of greater amounts of copper to improve fatigue strength.
U.S. Pat. No. 4,789,607 to Fujita et al. relates to an aluminum base alloy containing tin, silicon, lead, strontium and antimony. U.S. Pat. No. 4,822,561 granted to Kamiya discloses a bearing alloy comprising aluminum and minor amounts of tin and copper, together with either manganese or zirconium. Optionally, the alloy can include lead and silicon.